void koch_line(GLfloat *st, GLfloat *ed){
         glVertex2fv(st);
         glVertex2fv(ed);
}
void divide_koch_line(GLfloat *st, GLfloat *ed, int n){
         GLfloat a[2], b[2], c[2], d[2], e[2];
         if( n>0 ){
                  a[0] = st[0];
                  a[1] = st[1];
                  e[0] = ed[0];
                  e[1] = ed[1];
                  b[0] = st[0] + (ed[0] - st[0])/3.0;
                  b[1] = st[1] + (ed[1] - st[1])/3.0;
                  d[0] = st[0] + (ed[0] - st[0])*2.0/3.0;
                  d[1] = st[1] + (ed[1] - st[1])*2.0/3.0;
                  c[0] = b[0]+(d[0]-b[0])*cos(60.0*3.1415/180.0)-(d[1]-b[1])*sin(60.0*3.1415/180.0);
                  c[1] = b[1]+(d[0]-b[0])*sin(60.0*3.1415/180.0)+(d[1]-b[1])*cos(60.0*3.1415/180.0);

                  divide_koch_line(a,b,n-1);
                  divide_koch_line(b,c,n-1);
                  divide_koch_line(c,d,n-1);
                  divide_koch_line(d,e,n-1);
         }
         else{
                  koch_line(st,ed);
         }
}

#include <stdio.h>
#include <Windows.h>
#include <tchar.h>
#include <stdlib.h>

void PrintConsoleScreen(const int nCurView, HANDLE hConsoleBuf[2], LPCTSTR lpCharacter, COORD dwWriteCoord);
void UpdateScreen(int *nCurView, HANDLE hConsoleBuf[2]);

void DrawRectangle(){
 char Mark[21][3] = { "☆","★","○","●","◎","◇","◆","□","■","△","▲","▽","▼","◈","▣","♤","♠","♡","♥","♧","♣"};
 int x,y;
 system("cls");
 for(y=0; y<20; y++){
  for(x=0; x<30; x++){
   printf("%s", Mark[rand()%21]);
  }
  printf("\n");
 }
}

void DrawRectangleBuffering(int *nCurView, HANDLE hConsoleBuf[2]){
 COORD pos = {0, 0};
 int x,y;
 
 LPCTSTR Mark[21] = { _T("☆"),_T("★"),_T("○"),_T("●"),_T("◎"),_T("◇"),_T("◆"),_T("□"),_T("■"),_T("△"),_T("▲"),_T("▽"),_T("▼"),_T("◈"),_T("▣"),_T("♤"),_T("♠"),_T("♡"),_T("♥"),_T("♧"),_T("♣")};
 
 for(y=0; y<20; y++){
  pos.Y = y;
  for(x=0; x<30; x++){
   pos.X = 2*x;
   PrintConsoleScreen(*nCurView, hConsoleBuf, Mark[rand()%21],  pos);
  }
 }
 UpdateScreen(nCurView, hConsoleBuf);
}

int main(int argc, const char *argv[]){
 HANDLE hConsoleBuf[2];
 int nCurView=0;
 bool bFlag;
 int i=0;
 hConsoleBuf[0] = CreateConsoleScreenBuffer(GENERIC_READ|GENERIC_WRITE, 0, NULL, CONSOLE_TEXTMODE_BUFFER, NULL);
 hConsoleBuf[1] = CreateConsoleScreenBuffer(GENERIC_READ|GENERIC_WRITE, 0, NULL, CONSOLE_TEXTMODE_BUFFER, NULL);
 while(i++<100){
  //DrawRectangleBuffering(&nCurView, hConsoleBuf);
  DrawRectangleA();
  Sleep(1000);
 }
 return 0;
}
void PrintConsoleScreen(const int nCurView, HANDLE hConsoleBuf[2], LPCTSTR lpCharacter, COORD dwWriteCoord)
{
 WriteConsoleOutputCharacter(hConsoleBuf[nCurView], lpCharacter, _tcslen(lpCharacter), dwWriteCoord, NULL);
}
void UpdateScreen(int *nCurView, HANDLE hConsoleBuf[2])
{
 SetConsoleActiveScreenBuffer(hConsoleBuf[*nCurView]);
 *nCurView = (*nCurView+1)%2;
}